Automotive air bags are commonly installed to protect both the driver and the front seat passenger from injury in the event of a head-on collision. The term "air bag" is something of a misnomer because, typically, the bag is filled with a rapidly evolving gas produced by an ignitor. The bag is designed to inflate in no more than approximately 50 milliseconds. In its uninflated and folded condition it is mounted within a housing having a cover which is designed to tear along predetermined lines to provide an opening for the escape of the air bag.
In view of the explosive nature of the air bag inflation, one of the major problems with prior art installations has been the tendency of the air bag cover to part from its housing or to break into pieces. The air bag cover or its pieces thereby become projectiles capable of inflicting damage on the occupants.
Various approaches have been employed in the prior art to overcome this problem. In one such approach, the plastic cover member is strengthened by embedding therein a fabric band made of a highly tear resistant material Such an approach, for example, is disclosed in U.S. Pat. No. 4,334,699 of Patzelt et al. In another approach disclosed in U.S. Pat. No. 5,092,627 of Igawa, the plastic cover is riveted to a metal plate which deforms as the cover breaks open. U.S. Pat. No. 4,968,057 of Rafferty discloses metal sheet inserts which are also riveted to the housing. Other approaches to the solving of these problems will be found in U.S. Pat. Nos. 4,148,503 of Shiratori et al., U.S. Pat. No. 4,852,907 of Shiraki et al., and U.S. Pat. No. 5,013,065 of Kreuzer.
One of the major problems with all of the prior art solutions is that they are expensive to implement and result in an undesirably heavy air bag installation. Furthermore, the covers lack flexibility with the result that they are not easily assembled. Accordingly, it is a primary object of the present invention to provide an air bag installation comprising a molded cover which requires no reinforcements. Another object is to provide such a cover which is sufficiently flexible that it may be readily assembled to the air bag housing. Another object is to provide such an assembly wherein the energy of the expanding air bag is dissipated in a managed way to prevent the cover from breaking up. Another object is to provide a cover which is designed so that, as it opens, it flexes in such a manner that it becomes more firmly secured to the housing. Other objects, features, and advantages will become apparent from the following description and appended claims.